I've tried looking this up on a search but can't seem to find the information I'm looking for.This question is for anyone who can answer but I'm also interested in what anyone from the UK who has cruised Alaska has to say.

As I'm from the UK...what happens when I do a Vancouver to Vancouver cruise, regarding entry to the USA via an Alaskan port. When I arrive in Vancouver I will be in Canada and getting on board the cruise ship will still be Canada.

So for us UK citizens normally when we enter the United States we have a green visa waiver form to fill in & pass through customs & immigration and get a stamp on our passports.

Does this happen at the first Alaskan port we get to ? Does the cruise line have to hold UK passports for the immigration process.
Then just before we dock back at Vancouver at the end of the cruise...how do we exit the USA ?
Normally when we leave the USA, immigration take back the green bit of the visa waiver they have clipped on our passport (to prove we have left the USA )

It stands for Immigration and Naturalization Service. It no longer exists though. I don't know the answer either. It would be best to call the particular cruise line you are sailing on for the requirements.

Thanks Dwayne, actually I am only looking at cruises to Alaska along with other choices, so I haven't actually chosen a cruise line yet. I just want to be clear in my head about what the procedures for uk citizens are.At least I have a bit more of an idea now that Kraftsinc has told me USA immigration & customs are at the cruise terminal in Vancouver.
But I'm still wondering who gets to remove the green visa waiver receipt they attach to your passport.
Because if it does not get back to USA immigration then re-entry to the USA at a later date may be awkward as you have to prove when you left the country.
Hope I'm not confusing you too much.

I thought INS was the name of it. However I know that you will be asked to report to another section with your passports. We will in the Waiting area with people from Europe, and Ireland last year. That is what happened to them.